SCIENCE- GOSSIP. 



219 



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CHEMISTRY 



CONDUCTED BY C. AINSWORTH MITCHELL, 

 B.A.OXON., F.I.C., F.C.S. 



Selenium in Beer— The element selenium has 

 recently attracted considerable attention from the 

 fact of its having been detected by Tunnicliffe and 

 Rosenheim in a sample of invert sugar, and in two 

 of the samples of the beer which caused the 

 epidemic of arsenical poisoning. Selenium, which 

 is closely allied to sulphur in its physical and 

 chemical properties, was discovered by Berzelius 

 in 1817 in a reddish-brown deposit in the leaden 

 chambers in which sulphuric acid had been manu- 

 factured. It is a common constituent of certain 

 varieties of iron pyrites used as the source of oil 

 of vitriol. Like sulphur, it can exist in several 

 modifications, and is known as a reddish-orange 

 deposit, a black vitreous mass, and in the form of 

 cry.-tals. It burns with a bluish flame, the vapours 

 of the combustion having a characteristic un- 

 pleasant odour. It combines with hydrogen to 

 form a poisonous gas, known as seleniuretted 

 hydrogen, which when passed through a hot narrow 

 glass tube is decomposed, leaving an orange mirror 

 of selenium on the cooler portion of the tube. It 

 combines with metals to form various selenides 

 which are analogous to the corresponding metallic 

 sulphides. When heated with sulphuric acid it 

 dissolves, forming a green solution, from which 

 the selenium can be separated again on adding a 

 large amount of water. It is said to produce 

 peripheral neuritis, resembling that of arsenical 

 poisoning, though the symptoms are much less 

 marked. Hence the theory was formed that 

 selenium played a distinct though subsidiary part 

 in the recent poisoning epidemic. As, however, 

 hundreds of other samples of beer have been 

 examined without its presence having been de- 

 tected, the conclusions drawn by Messrs. Tunnicliffe 

 and Rosenheim stand in need of confirmatory 

 experimental evidence. 



Alkaline Waters from the Chalk. — It has 

 frequently been noted that waters from deep wells 

 in London and other places where the chalk is 

 covered by a layer of clay differ completely in 

 character from waters obtained from the un- 

 covered chalk. Thus in a water of the former 

 class there are only traces of calcium carbonate 

 and magnesium carbonate, but considerable quan- 

 tities of alkaline salts, and the water is soft and 

 alkaline. On the other hand, in a typical water 

 from the uncovered chalk there is a large propor- 

 tion of calcium and magnesium carbonates which 

 render the water hard. Various theories, such as 

 the infiltration of sea water, have been proposed to 

 account for the occurrence of alkaline salts in the 

 chalk waters from beneath the clay, but the most 

 satisfactory explanation is that recently offered by 

 Mr. W. W. Fisher. He points out that the London 

 Clay offers an impervious barrier to the passage of 

 the water, which must therefore have slowly 

 travelled through the porous chalk from the out- 



side area, taking up in its passage the soluble salts 

 which are still present to a considerable extent in 

 chalk which has no natural outlet through which 

 these could have been washed away, as in the case 

 of the surface chalk. In this underground journey 

 the proportion of alkaline salts will gradually 

 increase, and the calcium salts show a continual 

 diminution. In support of this theory Mr. Fisher 

 gives the analysis of a specimen of chalk taken 

 from a boring 500 feet deep in the Tottenham 

 Court Road. This chalk was distinctly alkaline, 

 and contained 0-28 per cent, of sodium sulphate, 

 020 per cent, of sodium chloride, and 0-03 per cent, 

 of sodium carbonate. 



Artificial Production of Diamonds. — A pro- 

 cess has just been patented in this country by 

 A. Ludwig, of Bernburg, in Germany According 

 to this patent, carbon or graphite is heated by 

 means of an electric current in an atmosphere of a 

 gas, preferably hydrogen, which has been pre- 

 viously compressed to the required extent. The 

 temperature is raised to the point. at which the 

 carbon ceases to conduct and is converted into 

 diamond. 



Iron in Hens' Eggs. —Some interesting experi- 

 ments have been described by P. Hoffmann in the 

 " Zeit. Anal. Chem." It was found that on the 

 average the yolk of an egg contained twelve milli- 

 grammes of iron oxide, or that the entire egg 

 without its shell contained 1*8 milligramme. At- 

 tempts were then made to increase this proportion 

 by feeding the hens on an organic compound of 

 iron known as ferrohaemol, with the result that 

 the eggs contained a few milligrammns more of 

 iron, and that there was also an increased quantity 

 in the livers of the birds. In similar feeding- 

 experiments with organic preparations of copper 

 no copper passed into the eggs. 



Salicylic Acid in Strawberries. — Salicylic 

 acid, which is a derivative of phenol or carbolic 

 acid, was originally prepared from oil of winter- 

 green {Gaultheria), and from salicin, a compound 

 extracted from willow-bark, but is now manu- 

 factured by an artificial synthetical process. As it 

 possesses but little taste and has strong antiseptic 

 properties, it has been extensively used as a preser- 

 vative in various food -products. As regards its 

 influence on the human system there are diverse 

 opinions, but it is significant that the Paris 

 Academy of Science forbid even the smallest 

 addition of salicylates to food, as being liable to 

 cause injury where any weakness of the kidneys or 

 digestive organs exists. Hence there have been 

 many prosecutions of the vendors of foods thus 

 preserved, and considerable attention has been 

 given to the best methods of detecting salicylic 

 acid. A few months ago the Cu-toms authorities 

 in Brazil condemned several Portugue.-e wines on 

 the ground of their containing traces of the acid, 

 but it was subsequently demonstrated by M, da 

 Silva that certain Portuguese wines contained 

 normally a small quantity of a sub.-tance which, 

 like salicylic acid, gave a violet coloration with 

 iron salts. Still more recently Portes and Des- 

 moulieres have extracted a similar substance from 

 fresh strawberries, and have identified it beyond 

 doubt as salicylic acid. It was present in the pro- 

 portion of about one part in a million. As salicylic 

 acid is frequently added to jams as a preservative, 

 the fact of its being a normal constituent of straw- 

 berries is of great practical importance. 



